First, I am a lifetime platinum paid member of DNF. However, I primarly follow this forum. Not necessarily because it's free, but I like the community feel to it. I personally believe all forums should be free to get free expression.
Second, there are ways for a forum owner to make money on "free" forums. These include banner advertising and Google Adsense primarily. It so happens that RJ actually even shares adsense revenue on parts of this site. If money were the issued, the revenue sharing could be halted and diverted elsewhere. A forum owner can't ask that adsense or banners be clicked to up their revenue, but you should know that clicking on them helps the site owner. I don't advocate clicking just to click, but by all means if you see something of interest, this is the place to check it out since it helps your community and it's viability. RJ does have some other businesses as well including sales of some nice scripts. You can also support his efforts by giving him the business if they suit your needs. I'm somewhat surprised RJ really hasn't used this forum to promote them more. (The
domainsellerpro script is an excellent starter system for domain sales, which I use.)
Third, most (not all) moderators do it primarily because they want to. I don't know about this forum, but sometimes they get perks instead of pay, such as free sticky threads, banner placements, input into what
they want from the forum, or other free goodies. Sometimes, just getting the extra recognition and reputation may enhance their domain sales enough to outweigh the time costs of being a moderator.
Finally, the thing I like least about DNF is the "classes" of members, which seems to promote elitism. I would really hate to see this site go that way and send me to me second favorite forum, with the initials DS. If anyone really feels they NEED to enhance RJ's income or that of a moderator, you can always make a direct "tip" to them for their service, or donate some NP$ to them which they can use in the marketplace. Personally, I think the moderators and RJ do a great job and seem to have things well under control.
BTW, if the real reason behind the suggestion is to get the newbies or "kids" off the site, I'm against that. They are going to be in the domain market, forum or not, and I see it as in all our best interest that they learn from the pros rather than become cybersquatters and or head to the "dark side" of the industry which gives the whole industry a black eye. I welcome the chance to influence them in businesslike dealings and staying legal in this wild west of an industry.
"If it ain't broke, don't fix it."